1. Field of the Invention
The present invention relates to a tire testing machine that includes a collision preventing sensor used to prevent a collision between a tire outer shape measurement sensor and a tire.
2. Description of the Related Art
In a tire manufacturing line, a tire testing machine performs a tire test in which the uniformity (evenness) of a tire is measured. The measurement of the uniformity is performed in a manner such that a tire attached to a spindle shaft is pressed against a rotation drum, the spindle shaft or the rotation drum is rotationally driven, and a force variation occurring in the tire is measured as a uniformity waveform.
Further, in the tire testing machine, the diameter of the tire or the deformation amount (the uneven or undulated portion of the surface of the tire) in the radial direction and the lateral direction of the tire is also measured by a tire outer shape measurement sensor provided in the tire testing machine in addition to the measurement of the uniformity.
As a technique of detecting the deformation amount (the run-out) of the outer shape and the diameter of the tire attached to the spindle shaft, a technique of a tire testing machine disclosed in Japanese Patent No. 3216952 is known. The technique relates to a run-out device of a tire uniformity machine in which a slide frame that is movable in a reciprocating manner in the radial direction with respect to a subject inspection tire is equipped with sensors that detect the deformation amounts of both side wall portions, both shoulder portions, and a tread portion of the tire. Here, the run-out device of the tire uniformity machine includes a position adjustment unit that adjusts the positions of the sensors detecting the deformation amounts of both side wall portions in the tire axis direction, a position adjustment unit that adjusts the positions of the sensors detecting the deformation amounts of both shoulder portions and the tread portion in the tire axis direction, and a position adjustment unit that adjusts the positions of the sensors in the tire radial direction. That is, the slide frame that is movable in a reciprocating manner in the radial direction with respect to the tire is equipped with tire outer shape measurement sensors that respectively detect the deformation amounts of both side wall portions, both shoulder portions, and the tread portion of the tire.
The tire outer shape measurement sensor is adapted to be movable in a reciprocating manner with respect to the tire by the position adjustment units provided in the tire testing machine. Then, the position of the tire outer shape measurement sensor is adjusted in accordance with the size of the tire and the like. That is, in a case where the position of the tire outer shape measurement sensor is adjusted during the measurement of the outer shape of the tire, the position of the tire outer shape measurement sensor is determined by teaching for each tire in advance based on information on the diameter of the tire or the thickness of the tire.
However, there is a concern that the tire outer shape measurement sensor may collide with the tire due to the erroneous information on the diameter of the tire or the thickness of the tire input from an operator or the erroneous allocation of the tire input information for the conveyed tire. Further, there is a concern that the tire outer shape measurement sensor may collide with the tire due to the problem of a driving motor that extends an arm provided with the tire outer shape measurement sensor. Further, since the tire outer shape measurement sensor provided in the tire testing machine is very expensive, there is a need to prevent the damage caused by the collision with the tire.
In order to solve the above-described problems, the tire testing machine may be equipped with a collision preventing unit that detects a gap (a distance) between the tire outer shape measurement sensor and the tire and urgently stops the tire outer shape measurement sensor before the tire outer shape measurement sensor collides with the tire.
In the collision preventing unit, a contact detection type sensor (generally a limit switch) is used. Usually, the collision preventing sensor (the collision preventing unit) may be equipped with a bar-shaped probe, and the extension of the arm provided in the tire outer shape measurement sensor stops when the probe contacts the tire.
Incidentally, as illustrated in FIGS. 4A to 4C, a non-contact zone in which a bar-shaped probe 118 does not contact a tire T exists in each of the end portions (both shoulder portions) of a tire T attached to a rim 104 of a spindle shaft 102 in the width direction since the probe 118 moves along the outer peripheral surface of the tire T in a case where the probe 118 of a collision preventing sensor 117 of the related art is located at the outside (the upper and lower sides of the drawing paper of FIGS. 4A to 4C) in relation to the end portions of the tire T in the width direction. For this reason, a problem arises in that the probe 118 does not contact the tire T and a tire outer shape measurement sensor 116 contacts the tire T.
FIG. 4A is a view illustrating a case where the probe 118 extends in the horizontal direction with respect to the horizontal movement direction of the tire outer shape measurement sensor 116.
As illustrated in this drawing, when an arm portion 121 moves in the horizontal direction so that the probe 118 is located at the center portion of the tire T in the width direction, the contact of the probe 118 with respect to the tire T may be detected to a certain degree. However, when the probe 118 is located at the outside of the end portion of the tire T in the width direction, a non-contact zone in which the probe 118 does not contact the tire T exists. For this reason, there is a concern that the tire outer shape measurement sensor 116 may collide with the tire T.
FIG. 4B is a view illustrating a case where the probe 118 extends in the perpendicular direction with respect to the horizontal movement direction of the tire outer shape measurement sensor 116.
As illustrated in this drawing, when the arm portion 121 moves in the perpendicular direction so that the probe 118 is located at the center portion of the side wall portion of the tire T, the contact of the probe 118 with respect to the tire T may be detected to a certain degree. However, when the probe 118 is located at the outside (the outside of the outer peripheral surface of the tire T) in relation to the end portion of the tire T in the radial direction, a non-contact zone in which the probe 118 does not contact the tire T exists. For this reason, there is a concern that the tire outer shape measurement sensor 116 may collide with the tire T. Further, when the arm portion 121 moves in the horizontal direction so that the probe 118 is located at the center portion of the tread portion of the tire T, the contact of the probe 118 with respect to the tire T may not be detected since the probe 118 extends in the perpendicular direction.
FIG. 4C is a view illustrating a case where the probe 118 is disposed obliquely with respect to the horizontal movement direction of the tire outer shape measurement sensor 116 in order to solve the problems of FIGS. 4A and 4B. In this case, the contact of the tire T may be detected in a wide range with respect to the horizontal and perpendicular movements of the arm portion 121. However, even in this configuration, a non-contact zone in which the probe 118 does not contact the tire T exists. For this reason, there is a concern that the tire outer shape measurement sensor 116 may collide with the tire T.
For example, in the probe 118 that detects the lower surface of the side wall portion of the tire T, when the probe 118 moves in the horizontal direction and moves in the upward perpendicular direction so that the probe 118 approaches the surface (the side wall portion) of the tire T, the probe 118 enters the inner portion of the tire T (a non-contact zone in which the probe 118 does not contact the tire T occurs). For this reason, the tire outer shape measurement sensor 116 collides with the tire T (the example of the probe 118 that is located at the lower side of the tire T of FIG. 4C).
Further, even when the side wall portion of the tire T is bulged, the tire outer shape measurement sensor 116 collides with the bulged side wall portion before the probe 118 contacts the tire T (the example of the probe 118 located at the upper side of the tire T of FIG. 4C).
Therefore, the present invention is made in view of the above-described problems, and an object thereof is to provide a tire testing machine that includes a collision preventing sensor capable of reliably detecting a state where a gap between a tire outer shape measurement sensor and a tire becomes within a predetermined distance by eliminating a non-contact zone in which a probe of the collision preventing sensor does not contact the tire and of reliably preventing a collision between the tire outer shape measurement sensor and the tire.